Identification of the brown midrib genes bmr6 and bmr12 in Sorghum germplasms using an SNP marker

The brown midrib of sorghum was induced by chemical mutagens. Compared to the traditional white midrib sorghum, the brown midrib mutant can decrease lignin concentrations and enhance the digestibility of ruminants. Eight bmr genes have been identified in sorghum, of which bmr6 and bmr12 have been studied and widely used at a biological and molecular level. Currently, there is no method to differentiate the genotype of sorghum from the midrib color, with many germplasm resources of brown midrib sorghum. Hence, this study was performed based on the DNA sequence information of the bmr6 and bmr12 single-nucleotide mutations, using the biomarker technology of single-nucleotide polymorphisms (SNPs) to identify the bmr type individuals at the seedling stage in 51 sorghum germplasms. The results showed that 24 bmr6 sorghum germplasms were identified, which contained the high-generation inbred line material; two bmr12 sorghum germplasms (TxbmrB and Daka2BF₉) were identified. The current study identified bmr6 and bmr12 sorghum germplasms that can serve as donors of the bmr trait for the breeding of new bmr lines, and be developed as corresponding bmr parent lines, so as accelerate the breeding process of new sorghum bmr lines. Therefore, this study optimized systems of the bmr6 and bmr12 SNP molecular marker systems that can quickly and accurately identify the germplasm of bmr6 and bmr12 by sequencing technology, thereby accelerating the molecular breeding process of sorghum bmr lines.